<?php
class JSSDK {
  private $appId;
  private $appSecret;

  public function __construct($appId, $appSecret) {
    $this->appId = $appId;
    $this->appSecret = $appSecret;
  }

  public function getSignPackage() {
    $jsapiTicket = $this->getJsApiTicket();
    // 注意 URL 一定要动态获取，不能 hardcode.
    $protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' || $_SERVER['SERVER_PORT'] == 443) ? "https://" : "http://";
    $url = "$protocol$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";
    $timestamp = time();
    $nonceStr = $this->createNonceStr();
    // 这里参数的顺序要按照 key 值 ASCII 码升序排序
    $string = "jsapi_ticket=$jsapiTicket&noncestr=$nonceStr&timestamp=$timestamp&url=$url";
    $signature = sha1($string);
    $signPackage = array(
      "appId"     => $this->appId,
      "nonceStr"  => $nonceStr,
      "timestamp" => $timestamp,
      "url"       => $url,
      "signature" => $signature,
      "rawString" => $string
    );
    return $signPackage; 
  }

  private function createNonceStr($length = 16) {
    $chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    $str = "";
    for ($i = 0; $i < $length; $i++) {
      $str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
    }
    return $str;
  }

  private function getJsApiTicket() {
    $data = json_decode($this->get_php_file("jsapi_ticket.php"));
    if ($data->expire_time < time()) {
      $accessToken = $this->getAccessToken();
      $url = "https://qyapi.weixin.qq.com/cgi-bin/get_jsapi_ticket?access_token=$accessToken";
      $res = json_decode($this->httpGet($url));
      $ticket = @$res->ticket;
      if ($ticket) {
        $data->expire_time = time() + 7000;
        $data->jsapi_ticket = $ticket;
        $this->set_php_file("jsapi_ticket.php", json_encode($data));
      }
    }else{
      $ticket = $data->jsapi_ticket;
    }
    return $ticket;
  }

  public function getAccessToken() {
      $data = json_decode($this->get_php_file("access_token.php"));
      if ($data->expire_time < time() || !$data) {
          $url = "https://qyapi.weixin.qq.com/cgi-bin/gettoken?corpid=$this->appId&corpsecret=$this->appSecret";
          $res = json_decode($this->httpGet($url));
          $access_token = @$res->access_token;
          if($access_token){
                $data->expire_time = time() + 7000;
                $data->access_token = $access_token;
                $this->set_php_file("access_token.php", json_encode($data));
          }
      }else{
          $access_token = $data->access_token;
      }
      return $access_token;
  }

  private function httpGet($url){
     $curl = curl_init();
     curl_setopt($curl, CURLOPT_URL,$url);
     //针对ssl https协议
     curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
     curl_setopt($curl, CURLOPT_SSL_VERIFYHOST,false);
     curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
     //检测get post方式提交数据
     if(!empty($data)){
         //设置post方式提交
         curl_setopt($curl, CURLOPT_POST, 1);
         //设置post数据
         curl_setopt($curl, CURLOPT_POSTFIELDS, $data);
     }
     //执行命令
     $result = curl_exec($curl);
     //关闭URL请求
     curl_close($curl);
     //返回获得数据
     return $result;
  }

  private function get_php_file($filename) {
    return trim(substr(file_get_contents('./Org/Chat/'.$this->appId.'_'.$filename), 15));
  }
  private function set_php_file($filename, $content) {
    $fp = fopen('./Org/Chat/'.$this->appId.'_'.$filename, "w");
    fwrite($fp, "<?php exit();?>" . $content);
    fclose($fp);
  }
}